What could be the cause of this error? Sorry about the comments in the code being in German, but if you want I could translate them into English.

网友答案:

From what I recall, "AWT-EventQueue-0" exceptions are from when you do something asynchronous with the HashMap. I would highly recommend that you separate the view from the model! And if necessary, separate the controller as well:

http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller

Do you get a number from what line the execution stoped? As this would really help identify from where the problem starts. Also you could do a debugging on the code. I recommend the Eclipse (Indigo), as it has a good debugger built in and a lot of other neat stuff. It grows on you!

TIPS

Try following the question form:

http://stackoverflow.com/questions/how-to-ask

because it's really hard when you leave 3 pages of code that's not relevant at all!
(About the language; the comment and variable names in germen, I think, is not so hard to understand. I mean, I know what you're instantiating so the names could be "asdf" or "foobar" for all I care.)

Also, please do put the constructor for the class as the first method after deceleration of class variables; as this makes it much easier to quickly identify it.